Since the early phases of the global coronavirus disease (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), national and regional lockdowns have been instrumental in controlling the spread of the virus in many parts of the world. In most cases, those countries that were able to implement lockdowns early on in the pandemic were better able to manage the spread of SARS-CoV-2 among their populations.
New research by scientists in Brazil and the USA suggests that three primary factors have influenced the early macro-geographical dynamics of the COVID-19 pandemic in Brazil.
The study’s findings suggest that if a lockdown had been imposed earlier on in superspreader cities like São Paulo, mandatory road traffic restrictions had been enforced, and intensive care unit (ICU) beds had been allocated more equitably across geographical regions, Brazil’s experience of the COVID-19 pandemic might have been mitigated.
The team has published their study in the Nature Scientific Reports journal.
Brazil's fight against COVID-19
Although international airports served as main entry points for SARS-CoV-2, the factors that drove COVID-19's uneven geographical spread and deaths in Brazil remain unclear.
On March 27, 2929, Brazil announced a temporary ban on foreign air travel, and state governments imposed quarantine orders to prevent viral spread. Though the first COVID-19 case was reported on January 28, 2020, it was not until May 2020 that the number of cases reached more than 100,000. From there, the case continued to rise.
To date, the number of confirmed cases in Brazil has topped 18.38 million, with over 512,000 deaths, making it the third country in the world with the highest number of cases.
During the first three months of the pandemic in Brazil, São Paulo initially accounted for more than 85% of the caseload. However, even though the main entry points of SARS-CoV-2 were monitored and the main coronavirus genotypes were immediately identified, the routes taken by the virus to reach the entire country are still unknown.
Factors for viral spread
Understanding the geographical spread of infectious diseases requires analyzing several factors, including environmental factors, pathogen population traits, and the flow of people in the transportation network.
The researchers examined human-mediated processes that turned capital cities into SARS-CoV-2 "superspreaders" at the geographical scale in the current study. The team also aimed to shed light on the critical processes that accounted for the macro-geographical patterns of COVID-19 cases and deaths in Brazil.
To arrive at the study findings, the researchers came up with a mathematical model of epidemics. They did not only consider population density but other factors like complex transportation networks.
The team believed that transportation patterns might have influenced the uneven geographical distribution of COVID-19 deaths in the country. Thus, they identified the spreading cities and Brazilian federal roads that contributed to the definition of the geographical patterns of COVID-19 cases. Further, the team also shed light on how the distribution of intensive care unit (ICU) beds across the country influenced the uneven spatial distribution of COVID-19 deaths during the first six months of the COVID-19 pandemic.
The study findings showed that three major factors influenced the spread of COVID-19 in Brazil. These include having a super-spreading city, federal highways, and the country's ICU beds and facilities.
São Paulo initially accounted for more than 85 percent of the case spread in the whole country. By adding 16 other spreading cities, the team accounted for 98 to 99 percent of the cases during the first three months of the pandemic.
The team also added that federal highways played an imperative role in the viral spread. These accounted for about 30 percent of the SARS-CoV-2 spread. Lastly, the distribution of COVID-19 deaths started to correlate with the allocation of intensive care units (ICU).
The team thus suggests that if the country has imposed a lockdown in superspreading cities like São Paulo, the cases and the impact of COVID-19 would be lower. The team also notes that if mandatory road traffic restrictions had been imposed, and more equitable distributions of ICU beds were in effect, there would have been fewer cases – and ultimately fewer deaths – in the country.
- Nicolelis, M., Raimundo, R., Peixeto, P., Andreazzi, C. (2021). The impact of superspreader cities, highways, and intensive care availability in the early stages of the COVID-19 epidemic in Brazil. Nature Scientific Reports. https://doi.org/10.1038/s41598-021-92263-3, https://www.nature.com/articles/s41598-021-92263-3.